Remove skin from potatoes and mash coarsely. In large pot cook bacon until crisp. Drain on paper towels; crumble and set aside. In drippings add celery, onions, and garlic. Saute for about 5 minutes, until white part of onions is translucent. Add chicken broth, milk, salt and pepper to vegetables. Bring to boil. Reduce heat and simmer for 10 min. Stir in sour cream and reserved bacon. Serve soup garnished with shredded cheese. Serves 4.